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Novel Antimicrobials Protect Against Mastitis-Causing Bacteria / May
24, 2006 / News from the USDA Agricultural Research Service

In ARS lab studies, a new two-in-one
recombinant protein was developed, which kills several bacteria known to cause
mastitis in dairy cows. Last year ARS reported success by a different research
team in producing transgenic cows (including "GEM," above) that were protected
against a single major cause of mastitis, the bacterium Staphylococcus aureus.
Click the image for more information about it.

Novel Antimicrobials Protect Against Mastitis-Causing Bacteria

An Agricultural Research Service (ARS)-led team has combined specific DNA
segments from two different sources to produce a novel antimicrobial protein.
The resulting "fusion" antimicrobial protein degrades the cell walls of several
bacterial pathogens in a solution of whey extracted from cow's milk.

Agriculturally, the technology provides a key step to developing dairy
cows that have a natural, built-in defense against mastitisa disease that
costs U.S. dairy producers up to $2 billion annually.

In the realm of infectious disease, one way to reduce microbial
resistance that results from widespread antibiotic use is to come up with new
ways to fight pathogens. The findings from this experimental study were
published in the April 2006 issue of Applied Environmental Microbiology.

Donovan is the named inventor on a USDA/ARS-filed patent application
that describes the technology behind fusing the protein-coding DNA sequences
that produce the novel fusion antimicrobial. He and colleagues from Birmingham,
Ala., and Quebec, Canada, hope to use the technology to produce fusion proteins
as alternatives to the use of broad-range antibiotics both in clinics and on
farms.

While all milk contains several naturally occurring antimicrobial
proteins, such as lysozyme and lactoferrin, the sale of milk containing the
fusion protein would first require rigorous food safety testing and federal
regulatory approval.

Bacteria have layers of macromolecules that provide strength and shape
to their cell walls. The fusion antimicrobial protein, as a cell-wall-degrading
enzyme, kills pathogens by decomposing this structural layer and causing the
cell to break down.

The B30-lysostaphin fusion protein developed by Donovan's team is
active against both Staphylococcus aureus and three streptococcal
mastitis pathogens that together are responsible for up to 50 percent of the
dairy cattle mastitis that occurs in the United States.